1. Field of the Invention
The present invention relates generally to a pressure vessel, and in particular to an underwater pressure vessel that provides a substantially constant pressure environment in the vessel at sea level and in deep water, high external pressure conditions.
2. Prior Art
Underwater pressure vessels are used to maintain an internal environment that is dry and at a substantially constant internal pressure that is independent of potentially high external pressures, where the external pressures are a function of the vessel's depth in the water. Underwater pressure vessels are used for a variety of applications, such as providing a protective environment to house a source of power, a mechanical device, an electronic device and the like. Underwater pressure vessels typically have a cylindrical design, having a first end and second end. Their manufacture requires precision machining of both ends of a cylindrical body. The ends are fitted with end caps fabricated to close tolerances, sufficiently precise to seal the ends of the cylindrical vessel. Considerable machining setup time is required for fabrication of the cylinder and the two end caps, resulting in a significant portion of total product costs. Underwater pressure vessels can be outfitted to have sub-function capabilities of a system. Systems that have many elements require larger cylinders, and in circumstances where all the sub-function capabilities of the system are housed in the same pressure vessel, a considerable premium is paid to obtain a cylindrical stock piece that can house everything. Due to the cumbersome nature of larger stock pieces, there is a much higher probability of machining/fabrication errors, at a disproportionate rate based on the diameter of the stock piece.